The invention relates generally to a circuit for measuring waveforms of digital signals, and more specifically, to a circuit measuring a transition time of a digital signal. The invention relates further to a system for measuring a transition time of a digital signal.
Designing digital circuitry requires a clear design of signal timing and the right sequence of signals dependent on each other. Special focus is often on investigating time behavior, especially, on wave forms of critical signals, like, clock signals. In particularly, rising and falling edges of signals require special attention. Displaying this time behavior of these critical signals on and in integrated circuits is paramount for the functionality and reliability of VLSI chips. Besides the signal waveform in general, the slew rate is a relevant figure of merit and has to be monitored for meeting design requirements. One of the caveats is that the measurement has to be done on-chip because of the risk of distortions from the observed signal by external measurement equipment. Therefore, an on-chip waveform measurement method and system is appropriate which is enabled to measure wave forms of periodic signals and, among others, a skew adjustment circuit.